Question concerning present active participle

A line in the show I watching reads:

"Удывлены,не предполагали увидеть Льва Троцкого, раскатывающим тесто?"

which I translated as "Surprised? Did you not expect to see Leon Trotsky rolling dough?"

The question I have is about the word "раскатывающим" which looks to me like a present active participle. But aren't participles usually in the same case as the noun they describe? So why is "раскатывающим" in the instrumental (I think) instead of the animate accusative (gen.) "раскатывающого"

Participles can describe (and agree with) a noun, but the meaning would be different. The other function of adjectives/participles in the instrumental case is to be a predicative and collocate with a link verb: быть/выглядеть/казаться/... усталым (счастливым, несчастным, .... раскатывающим тесто))) Here it's a part of the predicate, but not an attribute describing Льва Троцкого.